During the spike, the system rewarded users with SBD, which is essentially debt. In order to get paid "real money", users either need to convert their SBD to STEEM, then sell their STEEM for BTC, or sell their SBD for BTC. Both put downward pressure on the price of SBD/STEEM. If there is more downward pressure (supply) than upward pressure (demand) then the price will go down.

"Normally" the system is supposed to balance such that the price of SBD remains close to 1 USD worth of STEEM. The problem is that the system created too much SBD during the spike that it is having a hard time holding that balance because there is just too much SBD supply.

They have taken some steps to reduce the SBD supply, but they are going to take time. (Doing it too quickly could crash the price.) We continue to look at other things that can be done too. For example right now I am buying up small amounts of SBD and converting at a loss to help reduce the supply.